Radio Frequency Circuit, Transmitter, Base Station, and User Terminal

ABSTRACT

The application provides a radio frequency circuit, including: a first circuit and a second circuit. The first circuit is configured to receive a first signal and a second signal; split the first signal into a third signal and a fourth signal, and split the second signal into a fifth signal and a sixth signal; adjust a phase of the fifth signal to obtain a seventh signal; and combine the seventh signal and the third signal into an eighth signal. The second circuit includes a primary power amplifier branch and a secondary power amplifier branch, and the primary power amplifier branch is configured to process the fourth signal and the sixth signal, and the secondary power amplifier branch is configured to process the eighth signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2014/093559, filed on Dec. 11, 2014, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the communications field, and inparticular, to a radio frequency circuit, a transmitter, a base station,and a user terminal.

BACKGROUND

In a radio base station, energy consumption of a radio frequency poweramplifier accounts for a very high proportion in total energyconsumption of the base station device. To reduce energy consumption, adual-input radio frequency circuit, for example, an outphasing circuit,or a Doherty (DHT) circuit including a primary power amplifier and asecondary power amplifier, is usually used to improve poweramplification efficiency. However, when the conventional dual-inputradio frequency circuit is used to improve back-off efficiency,efficiency between a power back-off point and a high power point may bereduced significantly. Finally, efficiency of a device, such as the basestation, for outputting a modulated wave is affected.

To improve the significantly reduced efficiency of the dual-input radiofrequency circuit, in the prior art, a DHT circuit and an outphasingcircuit are combined to form a composite radio frequency circuit. Thatis, the outphasing circuit is used as a primary power amplifier of theDHT circuit, and then a secondary power amplifier is added to performload modulation). The composite radio frequency circuit can effectivelyimprove the significantly reduced efficiency of the dual-input radiofrequency circuit between the power back-off point and the high powerpoint. However, a quantity of input signals of the dual-input radiofrequency circuit is increased from original two to three, andconsequently a size of the entire composite radio frequency circuitbecomes excessively large. In addition, to provide three input signalsto the composite radio frequency circuit, three transmit channels needto be disposed for the composite radio frequency circuit. Therefore, thecomposite radio frequency circuit has relatively high use costs,unfavorable to large-scale application and popularization.

To reduce a quantity of transmit channels, in a common prior-art method,signals transmitted on two transmit channels are converted into threeinput signals by performing an operation such as splitting orcombination, and the three input signals are connected to the compositeradio frequency circuit. However, after three input signals are obtainedby using this method, when the signals transmitted on the two transmitchannels are adjusted, at least one input signal cannot be adjusted toan expected value. Consequently, the composite radio frequency circuitat rated power cannot reach optimal power amplification efficiency, andoverall performance of the circuit is poor.

SUMMARY

Embodiments of the present disclosure provide a radio frequency circuit,so as to reach optimal power amplification efficiency. The embodimentsof the present disclosure further provide a transmitter, a base station,and a user terminal.

According to a first aspect, an embodiment of the present disclosureprovides a radio frequency circuit, including a first circuit and asecond circuit. The first circuit is configured to: receive a firstsignal and a second signal; split the first signal into a third signaland a fourth signal, and split the second signal into a fifth signal anda sixth signal; adjust a phase of the fifth signal to obtain a seventhsignal; and combine the seventh signal and the third signal into aneighth signal. The second circuit includes a primary power amplifierbranch and a secondary power amplifier branch, the primary poweramplifier branch includes an outphasing circuit, the secondary poweramplifier branch includes a secondary power amplifier, the outphasingcircuit is configured to process the fourth signal and the sixth signal,and the secondary power amplifier is configured to process the eighthsignal.

In a first possible implementation manner of the first aspect, the firstcircuit further includes a microstrip, the microstrip is configured toadjust the phase of the fifth signal, and a length of the microstrip isdirectly proportional to a phase shift of the fifth signal.

With reference to the foregoing possible implementation manner, in asecond possible implementation manner of the first aspect, the firstcircuit further includes an attenuation network and a combiner; theattenuation network is configured to attenuate the seventh signal andthe third signal; and the combiner is configured to combine theattenuated seventh signal and the attenuated third signal into theeighth signal.

With reference to either of the foregoing possible implementationmanners, in a third possible implementation manner of the first aspect,the first signal and the second signal are obtained by performing phasedecomposition on a modulated signal, including: a phase of the firstsignal is φ(t), a phase of the second signal is −φ(t), a value of φ(t)ranges from 0° to 90°, an amplitude of the first signal is equal to anamplitude of the second signal, φ(t) is a time-related function, t≧0,and t indicates time.

With reference to any one of the foregoing possible implementationmanners, in a fourth possible implementation manner of the first aspect,the secondary power amplifier being configured to process the eighthsignal includes: the eighth signal is input from a signal input end ofthe secondary power amplifier; and when an amplitude of the eighthsignal reaches a signal threshold, the secondary power amplifier isstarted to perform amplification processing on the eighth signal, wherethe signal threshold is a minimum signal amplitude required to start thesecondary power amplifier, and a value of a conduction angle of thesecondary power amplifier is greater than 120°.

According to a second aspect, an embodiment of the present disclosureprovides a transmitter, including the radio frequency circuit providedin the first aspect.

According to a third aspect, an embodiment of the present disclosureprovides a base station, including the transmitter provided in thesecond aspect, where the base station further includes a communicationsinterface, a processor, and a power supply.

According to a fourth aspect, an embodiment of the present disclosureprovides a user terminal, including the transmitter provided in thesecond aspect, where the user terminal further includes a memory, anexternal port, a peripheral interface, a processor, and a power supply.

The embodiments of the present disclosure provide a radio frequencycircuit, including: a first circuit and a second circuit. The firstcircuit is configured to: receive a first signal and a second signal;split the first signal into a third signal and a fourth signal, andsplit the second signal into a fifth signal and a sixth signal; adjust aphase of the fifth signal to obtain a seventh signal; and combine theseventh signal and the third signal into an eighth signal. The secondcircuit includes a primary power amplifier branch and a secondary poweramplifier branch, the primary power amplifier branch includes anoutphasing circuit, the secondary power amplifier branch includes asecondary power amplifier, the primary power amplifier branch isconfigured to process the fourth signal and the sixth signal, and thesecondary power amplifier branch is configured to process the eighthsignal. In the embodiments of the present disclosure, different firstsignals and second signals are corresponding to different fourth signalsand sixth signals, and the eighth signal may be controlled by performingphase adjustment on the fifth signal. Therefore, the fourth signal, thesixth signal, and the eighth signal that are input to the second circuitcan be adjusted to optimal parameters matching the second circuit, thesecond circuit at rated power can reach highest efficiency, performanceof a circuit is good, and an actual application requirement can besatisfied.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic structural diagram of a composite radio frequencycircuit in the prior art;

FIG. 2 is a schematic structural diagram of a radio frequency circuitaccording to an embodiment of the present disclosure;

FIG. 3 shows an input/output characteristic curve of a specific examplecircuit of a first circuit according to an embodiment of the presentdisclosure;

FIG. 4 is a schematic structural diagram of another radio frequencycircuit according to an embodiment of the present disclosure;

FIG. 5 shows a phase-phase curve of an eighth signal in a radiofrequency circuit according to an embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of a base station according toan embodiment of the present disclosure; and

FIG. 7 is a schematic structural diagram of a user terminal according toan embodiment of the present disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present disclosure provide a radio frequency circuit,to improve output power and efficiency of a circuit, and the followingprovides detailed description.

In the prior art, a composite radio frequency circuit includes a primarypower amplifier branch and a secondary power amplifier branch. For astructure of a circuit providing an input signal to the composite radiofrequency circuit, refer to FIG. 1. A signal transmitted on a firsttransmit channel is split into a signal {circle around (1)} and a signal{circle around (2)}, and a signal transmitted on a second transmitchannel is split into a signal {circle around (3)} and a signal {circlearound (4)}. The signal and the signal {circle around (3)} are used asinput of the primary power amplifier branch of the composite radiofrequency circuit, and a signal {circle around (5)} obtained bycombining the signal {circle around (2)} and the signal {circle around(4)} is used as input of the secondary power amplifier branch of thecomposite radio frequency circuit. Signal splitting and combination areimplemented by a circuit or component such as a coupler and a powersplitter, and a splitting rule depends on a characteristic of a circuitor component that performs splitting. For example, it is assumed that aphase shift of the circuit providing the input signal to the compositeradio frequency circuit is o, the signal transmitted on the firsttransmit channel is A₁e^(jφ) ¹ , the signal transmitted on the secondtransmit channel is A₂e^(jo) ² , and a power splitter ranging from 0° to90° is used to perform splitting and combination. After the splitting,the signal {circle around (1)} is

${\frac{A_{1}}{\sqrt{2}}e^{j\; \varphi_{1}}},$

the signal {circle around (2)} is

${\frac{A_{1}}{\sqrt{2}}e^{j{({\varphi_{1} - \frac{\pi}{2}})}}},$

the signal {circle around (3)} is

${\frac{A_{2}}{\sqrt{2}}e^{{- j}\; \varphi_{2}}},$

and the signal {circle around (4)} is

$\frac{A_{2}}{\sqrt{2}}{e^{- {j{({\varphi_{2} + \frac{\pi}{2}})}}}.}$

After the combination, the signal {circle around (5)} is

${\frac{A_{1}}{\sqrt{2}}e^{j{({\varphi_{1} - \pi})}}} + {\frac{A_{2}}{\sqrt{2}}{e^{- {j{({\varphi_{2} + \frac{\pi}{2}})}}}.}}$

A₁ is a peak of the signal transmitted on the first transmit channel, φ₁is a phase of the signal transmitted on the first transmit channel, A₂is a peak of the signal transmitted on the second transmit channel, andφ₂ is a phase of the signal transmitted on the second transmit channel.It may be learnt from the foregoing example that, after the circuitstructure is determined, the parameters A₁, φ₁, A₂, and φ₂ of the firsttransmit channel and the second transmit channel need to be adjusted toensure that amplitudes and phases of the signal {circle around (1)} andthe signal {circle around (3)} always are respective expected values.Consequently, an amplitude and a phase of the signal {circle around (5)}that is input to the secondary power amplifier branch is also unchangedand cannot be adjusted to an expected value of the signal {circle around(5)}. Regardless of how to adjust the signals transmitted on the firsttransmit channel and the second transmit channel, at least one of thesignal {circle around (1)}, the signal {circle around (3)}, or thesignal {circle around (5)} cannot be adjusted to an expected value.

To resolve the foregoing problem, an embodiment of the presentdisclosure provides a radio frequency circuit. For a schematicstructural diagram, refer to FIG. 2. The radio frequency circuit mainlyincludes a first circuit 201, configured to: receive a first signal anda second signal; split the first signal into a third signal and a fourthsignal, and split the second signal into a fifth signal and a sixthsignal; adjust a phase of the fifth signal to obtain a seventh signal;and combine the seventh signal and the third signal into an eighthsignal. The radio frequency circuit also includes a second circuit 202,including a primary power amplifier branch and a secondary poweramplifier branch, where the primary power amplifier branch includes anoutphasing circuit, the secondary power amplifier branch includes asecondary power amplifier, the outphasing circuit is configured toprocess the fourth signal and the sixth signal, and the secondary poweramplifier is configured to process the eighth signal.

The first signal and the second signal are input signals of the firstcircuit 201, and different first signals and second signals arecorresponding to different fourth signals and sixth signals.Specifically, after being split, different first signals arecorresponding to different fourth signals; and after being split,different second signals are corresponding to different sixth signals.

The seventh signal obtained by performing phase adjustment on the fifthsignal obtained by splitting the second signal is combined with thethird signal obtained by splitting the first signal, to form the eighthsignal. Therefore, different degrees of phase shifts occur on the fifthsignal by performing phase adjustment on the fifth signal, and theeighth signal can be controlled.

This embodiment provides a radio frequency circuit, including a firstcircuit 201 and a second circuit 202. It may be understood that thesecond circuit 202 at rated power can reach highest efficiency only whenall three input signals that are input to the second circuit 202 areadjusted to optimal parameters matching the second circuit 202. In thisembodiment, a fourth signal and a sixth signal may be controlled byadjusting a first signal and a second signal, and an eighth signal maybe controlled by performing phase adjustment on a fifth signal. In thisway, all the fourth signal, the sixth signal, and the eighth signal thatare input to the second circuit 202 can be flexibly adjusted to theoptimal parameters matching the second circuit 202, the second circuit202 at the rated power can reach highest efficiency, and an actualapplication requirement can be satisfied.

Optionally, the first circuit 201 further includes a microstrip,configured to adjust the phase of the fifth signal. A length of themicrostrip is directly proportional to a phase shift of the fifthsignal. A longer microstrip leads to a larger phase shift of the fifthsignal. Alternatively, in this embodiment of the present disclosure, adelay line, a variable capacitance diode, a phase shifter, or anothercircuit or component may be used to adjust the phase of the fifthsignal. This is not limited herein.

Optionally, in another embodiment of the present disclosure, the firstsignal and the second signal may be obtained by performing phasedecomposition on a modulated signal in a digital domain. The firstsignal and the second signal have identical amplitudes and reversephases. The amplitudes or the phases of the first signal and the secondsignal may be adjusted by adjusting an amplitude or a phase of themodulated signal. The modulated signal is usually obtained by performingenvelope modulation on a sine wave signal. When the phase decompositionis performed in the digital domain, a correspondence between theamplitude of the modulated signal and a decomposition phase of themodulated signal is as follows:

$\begin{matrix}{{{\phi (t)} = {\arccos \frac{r(t)}{r_{\max}}}},} & (1)\end{matrix}$

where φ(t) indicates an instantaneous value of the decomposition phaseof the modulated signal, r(t) indicates an instantaneous value of theamplitude of the modulated signal, r_(max) indicates a peak of theamplitude of the modulated signal, φ(t) is a time-related function, t≧0,t indicates time, and 0<φ(t)<90°.

It may be learnt from formula (1) that the decomposition phase of themodulated signal varies with the amplitude of the modulated signal. At aspecific moment, a larger amplitude of the modulate signal leads to asmaller decomposition phase of the modulate signal, or a smalleramplitude of the modulated signal leads to a larger decomposition phaseof the modulate signal.

After the phase decomposition described in formula (1) is performed, themodulated signal is decomposed into the first signal and the secondsignal. Amplitudes of the first signal and the second signal are equaland not greater than r_(max), the phase of the first signal is φ(t), andthe phase of the second signal is −φ(t).

The amplitudes of the first signal and the second signal are equal. Theamplitudes and the phases vary with time. Therefore, amplitudes andphases of the third signal, the fourth signal, the fifth signal, and thesixth signal that are obtained after the splitting, and the seventhsignal obtained by performing phase adjustment on the fifth signal alsovary with time. Because the eighth signal is obtained by combining theseventh signal and the third signal, an amplitude of the eighth signalis related to the phases of the seventh signal and the third signal.Phase adjustment is performed on the fifth signal, so that differentdegrees of shifts occur on the phase of the fifth signal, and obtainedeighth signals have different phase-amplitude curves. For a specificapplication example, refer to FIG. 3.

FIG. 3 shows an input/output characteristic curve of a specific examplecircuit of the first circuit 201. A horizontal coordinate axis indicatesthe decomposition phase of the modulated signal, that is, a phase valueof the first signal. A vertical coordinate axis indicates a voltageamplitude that is of the eighth signal and that is obtained bynormalizing a maximum voltage value of the modulated signal. Differentcurves indicate eighth signals corresponding to different phase shiftsof the fifth signal. Curve 1 indicates an eighth signal when a phaseshift of the fifth signal is 0 (that is, phase adjustment is notperformed). Curve 2 indicates a corresponding eighth signal when a phaseshift of the fifth signal is 20°. Curve 3 indicates a correspondingeighth signal when a phase shift of the fifth signal is 40°. For ease ofcomparison, a phase-amplitude curve of the modulated signal, that is,curve 0, is also added to FIG. 3.

It may be learnt from a comparison between curve 2 or 3 and curve 1 thatan amplitude value of the eighth signal becomes smaller after a phase ofthe fifth signal is adjusted. It may be learnt from a comparison betweencurve 2 and curve 3 that an amplitude value of the eighth signal may becontrolled by adjusting a phase shift of the fifth signal, and a largerphase shift of the fifth signal leads to a smaller amplitude of theeighth signal.

The second circuit 202 includes the primary power amplifier branch andthe secondary power amplifier branch. The primary power amplifier branchincludes the outphasing circuit, and the secondary power amplifierbranch includes the secondary power amplifier. The outphasing circuitusually operates in a class B or class AB condition, and the secondarypower amplifier usually operates in a class C condition. When the secondcircuit 202 operates, the outphasing circuit remains enabled, but thesecondary power amplifier is not started at the beginning. The secondarypower amplifier is started to perform amplification processing on theeighth signal only when an amplitude of the eighth signal input to asignal input end of the secondary power amplifier reaches a minimumsignal amplitude that can start the secondary power amplifier, that is,reaches a signal threshold corresponding to a conduction angle. It maybe understood that, when an amplitude of the modulated signal isrelatively small, the decomposition phase of the modulated signal isrelatively large, the amplitude of the eighth signal is relativelysmall, and the secondary power amplifier is not started. When anamplitude of the modulated signal is relatively large, the decompositionphase of the modulated signal is relatively small, the amplitude of theeighth signal is relatively large, and the secondary power amplifier isstarted. Therefore, the secondary power amplifier is started only whenthe amplitude of the modulated signal is relatively large, and poweramplification efficiency of the circuit is improved.

In the prior art, a secondary power amplifier is usually adjusted to adeep class C (that is, a conduction angle of the secondary poweramplifier is relatively small, for example, 100°) condition by using agrid voltage bias, to ensure that the secondary power amplifier isstarted only when an amplitude of a signal that is input to thesecondary power amplifier reaches a signal threshold, and a smallerconduction angle of the secondary power amplifier leads to a largersignal threshold corresponding to the secondary power amplifier.However, if the conduction angle of the secondary power amplifier isrelatively small, after the secondary power amplifier is started, bothsaturation power and a gain of the second circuit 202 are severelyaffected. Consequently, saturation power of the radio frequency circuitis relatively small, a gain curve of the circuit is severely compressed,and an actual application requirement cannot be satisfied. If theconduction angle of the secondary power amplifier is increased byadjusting the grid voltage bias, the signal threshold corresponding tothe secondary power amplifier becomes small, so that the eighth signalcan reach the signal threshold even when the amplitude of the modulatedsignal is relatively small, and therefore the secondary power amplifieris started. However, because an amplitude of the input signal isrelatively small, power amplification efficiency of the radio frequencycircuit is relatively low. Therefore, in the prior art, the poweramplification efficiency and the saturation power of the radio frequencycircuit cannot be balanced. The power amplification efficiency of thecircuit is ensured at the expense of the saturation power and a linearcharacteristic of the circuit.

In this embodiment, the amplitude value of the eighth signal is adjustedby adjusting different phases of the fifth signal, and saturation powerof the circuit can be improved when power amplification efficiency ofthe circuit is ensured. Specifically, first, because the amplitude ofthe eighth signal becomes smaller, in this embodiment, the signalthreshold corresponding to the secondary power amplifier can be properlyreduced with an assurance that the eighth signal cannot reach the signalthreshold when the amplitude of the modulated signal is relativelysmall. Therefore, the power amplification efficiency of the circuit isensured. Second, in this embodiment, the signal threshold correspondingto the secondary power amplifier may be reduced, and therefore, thesecondary power amplifier can be adjusted to a light class C (that is,the conduction angle of the secondary power amplifier is relativelylarge. For the radio frequency circuit provided in the presentapplication, the conduction angle of the secondary power amplifier maybe a value greater than 120°, for example, 160°) by using the gridvoltage bias of the secondary power amplifier. In this way, after thesecondary power amplifier is started, saturation power of the secondcircuit 202 is increased. In conclusion, in this embodiment, thesaturation power of the second circuit 202 can be improved withoutreducing power amplification efficiency of the second circuit 202.

For example, in FIG. 3, a criterion for adjusting the fifth signal bythe microstrip or another circuit or component may be as follows: Thephase of the fifth signal is adjusted, so that a first phase value isgreater than a second phase value. The first phase value is a phasevalue of the first signal corresponding to an intersection point of thephase-amplitude curve of the eighth signal and the phase-amplitude curve(curve 0) of the modulated signal. The second phase value is a phasevalue of the first signal corresponding to a power back-off point of thesecond circuit. This can ensure that the secondary power amplifier canremain in a switch-off state during power back-off, and can be rapidlystarted when power of the eighth signal is greater than power at thepower back-off point.

Based on the embodiment shown in FIG. 2, an embodiment of the presentdisclosure further provides a more refined radio frequency circuit thatis configured to implement more additional functions after a firstsignal and a second signal are obtained by performing phasedecomposition on a modulated signal. Referring to FIG. 4, a basicstructure of the radio frequency circuit includes a first circuit 401and a second circuit 402.

The first circuit 401 is configured to: receive the first signal and thesecond signal, where the first signal and the second signal are obtainedby performing phase decomposition on the modulated signal; split thefirst signal into a third signal and a fourth signal, and split thesecond signal into a fifth signal and a sixth signal; and adjust a phaseof the fifth signal to obtain a seventh signal. Signal splitting may beimplemented by a circuit or a component such as a coupler or a powersplitter, and this is not limited herein. The phase of the fifth signalmay be adjusted by a microstrip, a delay line, a variable capacitancediode, a phase shifter, or another circuit or component, and this is notlimited herein. The first circuit 401 further includes an attenuationnetwork and a combiner. The attenuation network is configured toattenuate the seventh signal and the third signal. The combiner isconfigured to combine the attenuated seventh signal and the attenuatedthird signal into an eighth signal. The combiner may be a circuit or acomponent such as a coupler or a power splitter, and this is not limitedherein. The combiner may further include a microstrip, a delay line, avariable capacitance diode, a phase shifter, or another circuit orcomponent that is configured to perform phase adjustment on theattenuated third signal or the attenuated seventh signal, to compensatefor a phase shift of a circuit or a component such as a coupler or apower splitter.

The second circuit 402 is basically the same as the second circuit 202shown in FIG. 2, and details are not described herein again.

The attenuation network of the first circuit 401 attenuates the seventhsignal and the third signal, so that amplitudes of the seventh signaland the third signal can be adjusted. Referring to FIG. 5, when theamplitudes of the seventh signal and the third signal vary, a phase ofthe eighth signal obtained after combination varies.

In FIG. 5, curve 1 indicates a phase-phase curve of the eighth signalwhen the amplitude of the seventh signal is 1 V, the amplitude of thethird signal is 0.8 V, and a phase shift of the fifth signal is 30°. InFIG. 5, curve 2 indicates a phase-phase curve of the eighth signal whenthe amplitude of the seventh signal is attenuated to 0.8 V, theamplitude of the third signal is 1 V, and a phase shift of the fifthsignal is 30°. A horizontal coordinate axis indicates a decompositionphase of the modulated signal, and a vertical coordinate axis indicatesthe phase of the eighth signal. It may be learnt from FIG. 5 that, whenthe amplitudes of the seventh signal and the third signal vary, thephase of the eighth signal obtained after combination varies. Therefore,the phase of the eighth signal can be controlled by disposing anattenuation network to adjust the amplitudes of the seventh signal andthe third signal. Therefore, according to the radio frequency circuitprovided in the embodiment shown in FIG. 4, an AM-PM characteristic ofthe eighth signal can be adjusted, a linear correction effect of theradio frequency circuit is improved, and distortion of an output signalof the radio frequency circuit is reduced. The AM-PM characteristicrefers to that amplitude variation of the input signal causes avariation of a phase difference between an input signal of an amplifierand an output signal of the amplifier.

Optionally, in this embodiment of the present disclosure, componentssuch as the microstrip or another circuit or component for adjusting thephase of the fifth signal, the attenuation network, and/or the combinermay be replaced with a chip having an amplitude modulation and/or aphase modulation function. This is not limited in this embodiment of thepresent disclosure.

An embodiment of the present disclosure further provides a transmitterincluding the radio frequency circuit described in FIG. 2 or FIG. 4. Thetransmitter provided in this embodiment of the present disclosure may beused in a radio frequency part of a base station, for example, in aremote radio unit (RRU), or may be used in a base transceiver station(BTS), or may be used in a user terminal, or may be used in anothercommunications apparatus or device. This is not limited herein.

Still further, referring to FIG. 6, an embodiment of the presentdisclosure further provides a base station including a communicationsinterface 601, a processor 602, a power supply 603, and a transmitter604. The transmitter 604 is the transmitter described in the foregoingembodiment. It may be understood that the base station provided in thisembodiment of the present disclosure may further include some otherstructures such as general-purpose apparatus, modules, and circuits thatare not shown in this figure.

Still further, an embodiment of the present disclosure further providesa user terminal including a memory 701, an external port 702, atransmitter 703, a peripheral interface 704, a processor 705, and apower supply 706. The transmitter 703 is the transmitter described inthe foregoing embodiment. It may be understood that the user terminalprovided in this embodiment of the present disclosure may furtherinclude some other structures such as general-purpose apparatus,modules, and circuits that are not shown in this figure.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the foregoing system, module, and unit, reference may be madeto a corresponding process in the foregoing method embodiments, anddetails are not described herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system and method may be implemented inother manners. For example, the described system embodiment is merely anexample. For example, the unit division is merely logical functiondivision and may be other division in actual implementation. Forexample, a plurality of units or components may be combined orintegrated into another system, or some features may be ignored or notperformed. In addition, the displayed or discussed mutual couplings ordirect couplings or communication connections may be implemented byusing some interfaces. The indirect couplings or communicationconnections between the modules or units may be implemented inelectronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected according toactual needs to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of the presentdisclosure may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit. The integrated unit may be implemented in a form ofhardware, or may be implemented in a form of a software functional unit.

When the integrated unit is implemented in the form of a softwarefunctional unit and sold or used as an independent product, theintegrated unit may be stored in a computer-readable storage medium.Based on such an understanding, the technical solutions of the presentdisclosure essentially, or the part contributing to the prior art, orall or some of the technical solutions may be implemented in the form ofa software product. The software product is stored in a storage mediumand includes several instructions for instructing a computer device(which may be a personal computer, a server, or a network device) toperform all or some of the steps of the methods described in theembodiments of the present disclosure. The foregoing storage mediumincludes: any medium that can store program code, such as a USB flashdrive, a removable hard disk, a read-only memory (ROM), a random accessmemory (RAM), a magnetic disk, or an optical disc.

What is claimed is:
 1. A radio frequency circuit, comprising: a firstcircuit, configured to: receive a first signal and a second signal;split the first signal into a third signal and a fourth signal, andsplit the second signal into a fifth signal and a sixth signal; adjust aphase of the fifth signal to obtain a seventh signal; and combine theseventh signal and the third signal into an eighth signal; and a secondcircuit, comprising: a primary power amplifier branch comprising anoutphasing circuit, wherein the outphasing circuit is configured toprocess the fourth signal and the sixth signal; and a secondary poweramplifier branch comprising a secondary power amplifier, wherein thesecondary power amplifier is configured to process the eighth signal. 2.The radio frequency circuit according to claim 1, wherein the firstcircuit further comprises a microstrip, the microstrip is configured toadjust the phase of the fifth signal, and a length of the microstrip isdirectly proportional to a phase shift of the fifth signal.
 3. The radiofrequency circuit according to claim 2, wherein the first circuitfurther comprises an attenuation network and a combiner; wherein theattenuation network is configured to attenuate the seventh signal andthe third signal; and wherein the combiner is configured to combine theattenuated seventh signal and the attenuated third signal into theeighth signal.
 4. The radio frequency circuit according to claim 3,wherein the first signal and the second signal are obtained byperforming phase decomposition on a modulated signal; and wherein aphase of the first signal is φ(t), a phase of the second signal is−φ(t), a value of φ(t) ranges from 0° to 90°, an amplitude of the firstsignal is equal to an amplitude of the second signal, φ(t) is atime-related function, t≧0, and t indicates time.
 5. The radio frequencycircuit according to claim 2, wherein the first signal and the secondsignal are obtained by performing phase decomposition on a modulatedsignal; and wherein a phase of the first signal is φ(t), a phase of thesecond signal is −φ(t), a value of φ(t) ranges from 0° to 90°, anamplitude of the first signal is equal to an amplitude of the secondsignal, φ(t) is a time-related function, t≧0, and t indicates time. 6.The radio frequency circuit according to claim 5, wherein the eighthsignal is input from a signal input end of the secondary poweramplifier; wherein, when an amplitude of the eighth signal reaches asignal threshold, the secondary power amplifier is started to performamplification processing on the eighth signal, wherein the signalthreshold is a minimum signal amplitude required to start the secondarypower amplifier; and wherein a value of a conduction angle of thesecondary power amplifier is greater than 120°.
 7. A base station,comprising a transmitter that comprises the radio frequency circuitaccording to claim 6, wherein the base station further comprises acommunications interface, a processor, and a power supply.
 8. A userterminal, comprising a transmitter that comprises the radio frequencycircuit according to claim 6, wherein the user terminal furthercomprises a memory, an external port, a radio frequency circuit, aperipheral interface, a processor, and a power supply.
 9. The radiofrequency circuit according to claim 5, wherein the eighth signal isinput from a signal input end of the secondary power amplifier; wherein,when an amplitude of the eighth signal reaches a signal threshold, thesecondary power amplifier is started to perform amplification processingon the eighth signal, wherein the signal threshold is a minimum signalamplitude required to start the secondary power amplifier; and wherein avalue of a conduction angle of the secondary power amplifier is greaterthan 120°.
 10. A transmitter, comprising a radio frequency circuitwherein the radio frequency circuit comprises: a first circuit,configured to: receive a first signal and a second signal; split thefirst signal into a third signal and a fourth signal, and split thesecond signal into a fifth signal and a sixth signal; adjust a phase ofthe fifth signal to obtain a seventh signal; and combine the seventhsignal and the third signal into an eighth signal; and a second circuit,comprising a primary power amplifier branch and a secondary poweramplifier branch, wherein the primary power amplifier branch comprisesan outphasing circuit and the secondary power amplifier branch comprisesa secondary power amplifier, and wherein the outphasing circuit isconfigured to process the fourth signal and the sixth signal, and thesecondary power amplifier is configured to process the eighth signal.